1. Field of the Invention
Oxalic acid is a constituent of barley. The amount of barley used as malt in beer brewing, contributes approximately 30-60 ppm (2-4.times.10.sup.-7 M) oxalic acid (as calcium oxalate) to wort. This level must be lowered to less than about 15 ppm in finished beer to prevent the problem of "gushing," whereby beer gushes from the bottle when opened. Currently, removal of oxalic acid is achieved by precipitation. During mashing, calcium is added to the malt-water mixture to stabilize and activate amylases. The presence of calcium ions forms insoluble calcium oxalate, which deposits on the walls of tanks during beer fermentation and maturation. This precipitate ("beerstone") harbors contaminating microorganisms and must be removed after each fermentation by scrubbing with a solution of a chelating agent and alkali. Removal of the beerstone is both costly and labor intensive.
It would therefore be desirable to be able to avoid the production of beerstone. Any method must take into consideration the various stages of beer production and the effect any additive might have on the processing and quality of the final product.
2. Description of the Prior Art
The Practical Brewer, A Manual for the Brewing Industry, 2nd ed. (Broderick ed.), Master Brewers Assoc. of the Americas, 1977, and Modern Brewing Technology, (Findlay, ed.) Macmillan Press, N.Y. 1971 are texts providing general descriptions of the brewing process. Modern Brewing Technology, pp. 201-203 describes the various cleaning material used in cleaning fermentation tanks. The following references describe analytical procedures for detecting oxalate: Bernstein and Khan, Proc. A.M. Amer. Soc. Brew. Chem. 1973: 20-23 (Abstracts (1974) 80:583; and Haas and Fleischman, J. Agric. & Food Chem. (1961) 9:451-452 (Abstracts (1962) 68:211). The references describe the problems of oxalate and oxalate sediments in beer production: Burger et al., Proc. A.M. Amer. Soc. Brew. Chem 1956: 169-178; and Burger et al., ibid 1956: 179-192.